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4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
… | |
… | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
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53 | The newest version of this document is also available as a html-formatted |
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54 | web page you might find easier to navigate when reading it for the first |
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
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56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occurring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
57 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
58 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
59 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
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61 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
62 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
63 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
64 | watcher. |
68 | watcher. |
65 | |
69 | |
66 | =head1 FEATURES |
70 | =head2 FEATURES |
67 | |
71 | |
68 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
69 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
71 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
78 | |
82 | |
79 | It also is quite fast (see this |
83 | It also is quite fast (see this |
80 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
81 | for example). |
85 | for example). |
82 | |
86 | |
83 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
84 | |
88 | |
85 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
86 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
87 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
88 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
89 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
90 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
91 | |
95 | |
92 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
93 | |
97 | |
94 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
97 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
98 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
99 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
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104 | component C<stamp> might indicate, it is also used for time differences |
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105 | throughout libev. |
100 | |
106 | |
101 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
102 | |
108 | |
103 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
104 | library in any way. |
110 | library in any way. |
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109 | |
115 | |
110 | Returns the current time as libev would use it. Please note that the |
116 | Returns the current time as libev would use it. Please note that the |
111 | C<ev_now> function is usually faster and also often returns the timestamp |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
112 | you actually want to know. |
118 | you actually want to know. |
113 | |
119 | |
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120 | =item ev_sleep (ev_tstamp interval) |
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121 | |
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122 | Sleep for the given interval: The current thread will be blocked until |
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123 | either it is interrupted or the given time interval has passed. Basically |
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124 | this is a subsecond-resolution C<sleep ()>. |
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125 | |
114 | =item int ev_version_major () |
126 | =item int ev_version_major () |
115 | |
127 | |
116 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
117 | |
129 | |
118 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
119 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
120 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
121 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
122 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
123 | |
135 | |
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136 | These version numbers refer to the ABI version of the library, not the |
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137 | release version. |
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138 | |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
125 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
126 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
127 | not a problem. |
142 | not a problem. |
128 | |
143 | |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
144 | Example: Make sure we haven't accidentally been linked against the wrong |
130 | version. |
145 | version. |
… | |
… | |
245 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
246 | |
261 | |
247 | If you don't know what event loop to use, use the one returned from this |
262 | If you don't know what event loop to use, use the one returned from this |
248 | function. |
263 | function. |
249 | |
264 | |
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265 | The default loop is the only loop that can handle C<ev_signal> and |
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266 | C<ev_child> watchers, and to do this, it always registers a handler |
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267 | for C<SIGCHLD>. If this is a problem for your app you can either |
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268 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
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269 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
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270 | C<ev_default_init>. |
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271 | |
250 | The flags argument can be used to specify special behaviour or specific |
272 | The flags argument can be used to specify special behaviour or specific |
251 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
273 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
252 | |
274 | |
253 | The following flags are supported: |
275 | The following flags are supported: |
254 | |
276 | |
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266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
288 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
267 | override the flags completely if it is found in the environment. This is |
289 | override the flags completely if it is found in the environment. This is |
268 | useful to try out specific backends to test their performance, or to work |
290 | useful to try out specific backends to test their performance, or to work |
269 | around bugs. |
291 | around bugs. |
270 | |
292 | |
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293 | =item C<EVFLAG_FORKCHECK> |
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294 | |
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295 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
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296 | a fork, you can also make libev check for a fork in each iteration by |
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297 | enabling this flag. |
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298 | |
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299 | This works by calling C<getpid ()> on every iteration of the loop, |
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300 | and thus this might slow down your event loop if you do a lot of loop |
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301 | iterations and little real work, but is usually not noticeable (on my |
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302 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
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303 | without a syscall and thus I<very> fast, but my Linux system also has |
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304 | C<pthread_atfork> which is even faster). |
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305 | |
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306 | The big advantage of this flag is that you can forget about fork (and |
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307 | forget about forgetting to tell libev about forking) when you use this |
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308 | flag. |
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309 | |
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310 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
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311 | environment variable. |
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312 | |
271 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
313 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
272 | |
314 | |
273 | This is your standard select(2) backend. Not I<completely> standard, as |
315 | This is your standard select(2) backend. Not I<completely> standard, as |
274 | libev tries to roll its own fd_set with no limits on the number of fds, |
316 | libev tries to roll its own fd_set with no limits on the number of fds, |
275 | but if that fails, expect a fairly low limit on the number of fds when |
317 | but if that fails, expect a fairly low limit on the number of fds when |
276 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
318 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
277 | the fastest backend for a low number of fds. |
319 | usually the fastest backend for a low number of (low-numbered :) fds. |
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320 | |
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321 | To get good performance out of this backend you need a high amount of |
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322 | parallelity (most of the file descriptors should be busy). If you are |
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323 | writing a server, you should C<accept ()> in a loop to accept as many |
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324 | connections as possible during one iteration. You might also want to have |
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325 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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326 | readyness notifications you get per iteration. |
278 | |
327 | |
279 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
328 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
280 | |
329 | |
281 | And this is your standard poll(2) backend. It's more complicated than |
330 | And this is your standard poll(2) backend. It's more complicated |
282 | select, but handles sparse fds better and has no artificial limit on the |
331 | than select, but handles sparse fds better and has no artificial |
283 | number of fds you can use (except it will slow down considerably with a |
332 | limit on the number of fds you can use (except it will slow down |
284 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
333 | considerably with a lot of inactive fds). It scales similarly to select, |
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334 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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335 | performance tips. |
285 | |
336 | |
286 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
337 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
287 | |
338 | |
288 | For few fds, this backend is a bit little slower than poll and select, |
339 | For few fds, this backend is a bit little slower than poll and select, |
289 | but it scales phenomenally better. While poll and select usually scale like |
340 | but it scales phenomenally better. While poll and select usually scale |
290 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
341 | like O(total_fds) where n is the total number of fds (or the highest fd), |
291 | either O(1) or O(active_fds). |
342 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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343 | of shortcomings, such as silently dropping events in some hard-to-detect |
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344 | cases and rewiring a syscall per fd change, no fork support and bad |
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345 | support for dup. |
292 | |
346 | |
293 | While stopping and starting an I/O watcher in the same iteration will |
347 | While stopping, setting and starting an I/O watcher in the same iteration |
294 | result in some caching, there is still a syscall per such incident |
348 | will result in some caching, there is still a syscall per such incident |
295 | (because the fd could point to a different file description now), so its |
349 | (because the fd could point to a different file description now), so its |
296 | best to avoid that. Also, dup()ed file descriptors might not work very |
350 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
297 | well if you register events for both fds. |
351 | very well if you register events for both fds. |
298 | |
352 | |
299 | Please note that epoll sometimes generates spurious notifications, so you |
353 | Please note that epoll sometimes generates spurious notifications, so you |
300 | need to use non-blocking I/O or other means to avoid blocking when no data |
354 | need to use non-blocking I/O or other means to avoid blocking when no data |
301 | (or space) is available. |
355 | (or space) is available. |
302 | |
356 | |
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357 | Best performance from this backend is achieved by not unregistering all |
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358 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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359 | keep at least one watcher active per fd at all times. |
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360 | |
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361 | While nominally embeddeble in other event loops, this feature is broken in |
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362 | all kernel versions tested so far. |
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363 | |
303 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
364 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
304 | |
365 | |
305 | Kqueue deserves special mention, as at the time of this writing, it |
366 | Kqueue deserves special mention, as at the time of this writing, it |
306 | was broken on all BSDs except NetBSD (usually it doesn't work with |
367 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
307 | anything but sockets and pipes, except on Darwin, where of course its |
368 | with anything but sockets and pipes, except on Darwin, where of course |
308 | completely useless). For this reason its not being "autodetected" |
369 | it's completely useless). For this reason it's not being "autodetected" |
309 | unless you explicitly specify it explicitly in the flags (i.e. using |
370 | unless you explicitly specify it explicitly in the flags (i.e. using |
310 | C<EVBACKEND_KQUEUE>). |
371 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
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372 | system like NetBSD. |
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373 | |
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374 | You still can embed kqueue into a normal poll or select backend and use it |
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375 | only for sockets (after having made sure that sockets work with kqueue on |
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376 | the target platform). See C<ev_embed> watchers for more info. |
311 | |
377 | |
312 | It scales in the same way as the epoll backend, but the interface to the |
378 | It scales in the same way as the epoll backend, but the interface to the |
313 | kernel is more efficient (which says nothing about its actual speed, of |
379 | kernel is more efficient (which says nothing about its actual speed, of |
314 | course). While starting and stopping an I/O watcher does not cause an |
380 | course). While stopping, setting and starting an I/O watcher does never |
315 | extra syscall as with epoll, it still adds up to four event changes per |
381 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
316 | incident, so its best to avoid that. |
382 | two event changes per incident, support for C<fork ()> is very bad and it |
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383 | drops fds silently in similarly hard-to-detect cases. |
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384 | |
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385 | This backend usually performs well under most conditions. |
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386 | |
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387 | While nominally embeddable in other event loops, this doesn't work |
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388 | everywhere, so you might need to test for this. And since it is broken |
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389 | almost everywhere, you should only use it when you have a lot of sockets |
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390 | (for which it usually works), by embedding it into another event loop |
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391 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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392 | sockets. |
317 | |
393 | |
318 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
394 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
319 | |
395 | |
320 | This is not implemented yet (and might never be). |
396 | This is not implemented yet (and might never be, unless you send me an |
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397 | implementation). According to reports, C</dev/poll> only supports sockets |
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398 | and is not embeddable, which would limit the usefulness of this backend |
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399 | immensely. |
321 | |
400 | |
322 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
401 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
323 | |
402 | |
324 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
403 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
325 | it's really slow, but it still scales very well (O(active_fds)). |
404 | it's really slow, but it still scales very well (O(active_fds)). |
326 | |
405 | |
327 | Please note that solaris ports can result in a lot of spurious |
406 | Please note that solaris event ports can deliver a lot of spurious |
328 | notifications, so you need to use non-blocking I/O or other means to avoid |
407 | notifications, so you need to use non-blocking I/O or other means to avoid |
329 | blocking when no data (or space) is available. |
408 | blocking when no data (or space) is available. |
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409 | |
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410 | While this backend scales well, it requires one system call per active |
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411 | file descriptor per loop iteration. For small and medium numbers of file |
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412 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
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413 | might perform better. |
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414 | |
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415 | On the positive side, ignoring the spurious readyness notifications, this |
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416 | backend actually performed to specification in all tests and is fully |
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417 | embeddable, which is a rare feat among the OS-specific backends. |
330 | |
418 | |
331 | =item C<EVBACKEND_ALL> |
419 | =item C<EVBACKEND_ALL> |
332 | |
420 | |
333 | Try all backends (even potentially broken ones that wouldn't be tried |
421 | Try all backends (even potentially broken ones that wouldn't be tried |
334 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
422 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
335 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
423 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
336 | |
424 | |
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425 | It is definitely not recommended to use this flag. |
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426 | |
337 | =back |
427 | =back |
338 | |
428 | |
339 | If one or more of these are ored into the flags value, then only these |
429 | If one or more of these are ored into the flags value, then only these |
340 | backends will be tried (in the reverse order as given here). If none are |
430 | backends will be tried (in the reverse order as listed here). If none are |
341 | specified, most compiled-in backend will be tried, usually in reverse |
431 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
342 | order of their flag values :) |
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343 | |
432 | |
344 | The most typical usage is like this: |
433 | The most typical usage is like this: |
345 | |
434 | |
346 | if (!ev_default_loop (0)) |
435 | if (!ev_default_loop (0)) |
347 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
436 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
375 | Destroys the default loop again (frees all memory and kernel state |
464 | Destroys the default loop again (frees all memory and kernel state |
376 | etc.). None of the active event watchers will be stopped in the normal |
465 | etc.). None of the active event watchers will be stopped in the normal |
377 | sense, so e.g. C<ev_is_active> might still return true. It is your |
466 | sense, so e.g. C<ev_is_active> might still return true. It is your |
378 | responsibility to either stop all watchers cleanly yoursef I<before> |
467 | responsibility to either stop all watchers cleanly yoursef I<before> |
379 | calling this function, or cope with the fact afterwards (which is usually |
468 | calling this function, or cope with the fact afterwards (which is usually |
380 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
469 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
381 | for example). |
470 | for example). |
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471 | |
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472 | Note that certain global state, such as signal state, will not be freed by |
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473 | this function, and related watchers (such as signal and child watchers) |
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474 | would need to be stopped manually. |
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475 | |
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476 | In general it is not advisable to call this function except in the |
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477 | rare occasion where you really need to free e.g. the signal handling |
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478 | pipe fds. If you need dynamically allocated loops it is better to use |
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479 | C<ev_loop_new> and C<ev_loop_destroy>). |
382 | |
480 | |
383 | =item ev_loop_destroy (loop) |
481 | =item ev_loop_destroy (loop) |
384 | |
482 | |
385 | Like C<ev_default_destroy>, but destroys an event loop created by an |
483 | Like C<ev_default_destroy>, but destroys an event loop created by an |
386 | earlier call to C<ev_loop_new>. |
484 | earlier call to C<ev_loop_new>. |
387 | |
485 | |
388 | =item ev_default_fork () |
486 | =item ev_default_fork () |
389 | |
487 | |
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488 | This function sets a flag that causes subsequent C<ev_loop> iterations |
390 | This function reinitialises the kernel state for backends that have |
489 | to reinitialise the kernel state for backends that have one. Despite the |
391 | one. Despite the name, you can call it anytime, but it makes most sense |
490 | name, you can call it anytime, but it makes most sense after forking, in |
392 | after forking, in either the parent or child process (or both, but that |
491 | the child process (or both child and parent, but that again makes little |
393 | again makes little sense). |
492 | sense). You I<must> call it in the child before using any of the libev |
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493 | functions, and it will only take effect at the next C<ev_loop> iteration. |
394 | |
494 | |
395 | You I<must> call this function in the child process after forking if and |
495 | On the other hand, you only need to call this function in the child |
396 | only if you want to use the event library in both processes. If you just |
496 | process if and only if you want to use the event library in the child. If |
397 | fork+exec, you don't have to call it. |
497 | you just fork+exec, you don't have to call it at all. |
398 | |
498 | |
399 | The function itself is quite fast and it's usually not a problem to call |
499 | The function itself is quite fast and it's usually not a problem to call |
400 | it just in case after a fork. To make this easy, the function will fit in |
500 | it just in case after a fork. To make this easy, the function will fit in |
401 | quite nicely into a call to C<pthread_atfork>: |
501 | quite nicely into a call to C<pthread_atfork>: |
402 | |
502 | |
403 | pthread_atfork (0, 0, ev_default_fork); |
503 | pthread_atfork (0, 0, ev_default_fork); |
404 | |
504 | |
405 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
406 | without calling this function, so if you force one of those backends you |
|
|
407 | do not need to care. |
|
|
408 | |
|
|
409 | =item ev_loop_fork (loop) |
505 | =item ev_loop_fork (loop) |
410 | |
506 | |
411 | Like C<ev_default_fork>, but acts on an event loop created by |
507 | Like C<ev_default_fork>, but acts on an event loop created by |
412 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
508 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
413 | after fork, and how you do this is entirely your own problem. |
509 | after fork, and how you do this is entirely your own problem. |
|
|
510 | |
|
|
511 | =item unsigned int ev_loop_count (loop) |
|
|
512 | |
|
|
513 | Returns the count of loop iterations for the loop, which is identical to |
|
|
514 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
515 | happily wraps around with enough iterations. |
|
|
516 | |
|
|
517 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
518 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
519 | C<ev_prepare> and C<ev_check> calls. |
414 | |
520 | |
415 | =item unsigned int ev_backend (loop) |
521 | =item unsigned int ev_backend (loop) |
416 | |
522 | |
417 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
523 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
418 | use. |
524 | use. |
… | |
… | |
421 | |
527 | |
422 | Returns the current "event loop time", which is the time the event loop |
528 | Returns the current "event loop time", which is the time the event loop |
423 | received events and started processing them. This timestamp does not |
529 | received events and started processing them. This timestamp does not |
424 | change as long as callbacks are being processed, and this is also the base |
530 | change as long as callbacks are being processed, and this is also the base |
425 | time used for relative timers. You can treat it as the timestamp of the |
531 | time used for relative timers. You can treat it as the timestamp of the |
426 | event occuring (or more correctly, libev finding out about it). |
532 | event occurring (or more correctly, libev finding out about it). |
427 | |
533 | |
428 | =item ev_loop (loop, int flags) |
534 | =item ev_loop (loop, int flags) |
429 | |
535 | |
430 | Finally, this is it, the event handler. This function usually is called |
536 | Finally, this is it, the event handler. This function usually is called |
431 | after you initialised all your watchers and you want to start handling |
537 | after you initialised all your watchers and you want to start handling |
… | |
… | |
452 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
558 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
453 | usually a better approach for this kind of thing. |
559 | usually a better approach for this kind of thing. |
454 | |
560 | |
455 | Here are the gory details of what C<ev_loop> does: |
561 | Here are the gory details of what C<ev_loop> does: |
456 | |
562 | |
457 | * If there are no active watchers (reference count is zero), return. |
563 | - Before the first iteration, call any pending watchers. |
458 | - Queue prepare watchers and then call all outstanding watchers. |
564 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
565 | - If a fork was detected, queue and call all fork watchers. |
|
|
566 | - Queue and call all prepare watchers. |
459 | - If we have been forked, recreate the kernel state. |
567 | - If we have been forked, recreate the kernel state. |
460 | - Update the kernel state with all outstanding changes. |
568 | - Update the kernel state with all outstanding changes. |
461 | - Update the "event loop time". |
569 | - Update the "event loop time". |
462 | - Calculate for how long to block. |
570 | - Calculate for how long to sleep or block, if at all |
|
|
571 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
572 | any active watchers at all will result in not sleeping). |
|
|
573 | - Sleep if the I/O and timer collect interval say so. |
463 | - Block the process, waiting for any events. |
574 | - Block the process, waiting for any events. |
464 | - Queue all outstanding I/O (fd) events. |
575 | - Queue all outstanding I/O (fd) events. |
465 | - Update the "event loop time" and do time jump handling. |
576 | - Update the "event loop time" and do time jump handling. |
466 | - Queue all outstanding timers. |
577 | - Queue all outstanding timers. |
467 | - Queue all outstanding periodics. |
578 | - Queue all outstanding periodics. |
468 | - If no events are pending now, queue all idle watchers. |
579 | - If no events are pending now, queue all idle watchers. |
469 | - Queue all check watchers. |
580 | - Queue all check watchers. |
470 | - Call all queued watchers in reverse order (i.e. check watchers first). |
581 | - Call all queued watchers in reverse order (i.e. check watchers first). |
471 | Signals and child watchers are implemented as I/O watchers, and will |
582 | Signals and child watchers are implemented as I/O watchers, and will |
472 | be handled here by queueing them when their watcher gets executed. |
583 | be handled here by queueing them when their watcher gets executed. |
473 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
584 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
474 | were used, return, otherwise continue with step *. |
585 | were used, or there are no active watchers, return, otherwise |
|
|
586 | continue with step *. |
475 | |
587 | |
476 | Example: Queue some jobs and then loop until no events are outsanding |
588 | Example: Queue some jobs and then loop until no events are outstanding |
477 | anymore. |
589 | anymore. |
478 | |
590 | |
479 | ... queue jobs here, make sure they register event watchers as long |
591 | ... queue jobs here, make sure they register event watchers as long |
480 | ... as they still have work to do (even an idle watcher will do..) |
592 | ... as they still have work to do (even an idle watcher will do..) |
481 | ev_loop (my_loop, 0); |
593 | ev_loop (my_loop, 0); |
… | |
… | |
485 | |
597 | |
486 | Can be used to make a call to C<ev_loop> return early (but only after it |
598 | Can be used to make a call to C<ev_loop> return early (but only after it |
487 | has processed all outstanding events). The C<how> argument must be either |
599 | has processed all outstanding events). The C<how> argument must be either |
488 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
600 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
489 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
601 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
602 | |
|
|
603 | This "unloop state" will be cleared when entering C<ev_loop> again. |
490 | |
604 | |
491 | =item ev_ref (loop) |
605 | =item ev_ref (loop) |
492 | |
606 | |
493 | =item ev_unref (loop) |
607 | =item ev_unref (loop) |
494 | |
608 | |
… | |
… | |
499 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
613 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
500 | example, libev itself uses this for its internal signal pipe: It is not |
614 | example, libev itself uses this for its internal signal pipe: It is not |
501 | visible to the libev user and should not keep C<ev_loop> from exiting if |
615 | visible to the libev user and should not keep C<ev_loop> from exiting if |
502 | no event watchers registered by it are active. It is also an excellent |
616 | no event watchers registered by it are active. It is also an excellent |
503 | way to do this for generic recurring timers or from within third-party |
617 | way to do this for generic recurring timers or from within third-party |
504 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
618 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
619 | (but only if the watcher wasn't active before, or was active before, |
|
|
620 | respectively). |
505 | |
621 | |
506 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
622 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
507 | running when nothing else is active. |
623 | running when nothing else is active. |
508 | |
624 | |
509 | struct ev_signal exitsig; |
625 | struct ev_signal exitsig; |
… | |
… | |
513 | |
629 | |
514 | Example: For some weird reason, unregister the above signal handler again. |
630 | Example: For some weird reason, unregister the above signal handler again. |
515 | |
631 | |
516 | ev_ref (loop); |
632 | ev_ref (loop); |
517 | ev_signal_stop (loop, &exitsig); |
633 | ev_signal_stop (loop, &exitsig); |
|
|
634 | |
|
|
635 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
636 | |
|
|
637 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
638 | |
|
|
639 | These advanced functions influence the time that libev will spend waiting |
|
|
640 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
641 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
642 | |
|
|
643 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
644 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
645 | increase efficiency of loop iterations. |
|
|
646 | |
|
|
647 | The background is that sometimes your program runs just fast enough to |
|
|
648 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
649 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
650 | events, especially with backends like C<select ()> which have a high |
|
|
651 | overhead for the actual polling but can deliver many events at once. |
|
|
652 | |
|
|
653 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
654 | time collecting I/O events, so you can handle more events per iteration, |
|
|
655 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
656 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
657 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
658 | |
|
|
659 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
660 | to spend more time collecting timeouts, at the expense of increased |
|
|
661 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
662 | will not be affected. Setting this to a non-null value will not introduce |
|
|
663 | any overhead in libev. |
|
|
664 | |
|
|
665 | Many (busy) programs can usually benefit by setting the io collect |
|
|
666 | interval to a value near C<0.1> or so, which is often enough for |
|
|
667 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
668 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
669 | as this approsaches the timing granularity of most systems. |
518 | |
670 | |
519 | =back |
671 | =back |
520 | |
672 | |
521 | |
673 | |
522 | =head1 ANATOMY OF A WATCHER |
674 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
622 | =item C<EV_FORK> |
774 | =item C<EV_FORK> |
623 | |
775 | |
624 | The event loop has been resumed in the child process after fork (see |
776 | The event loop has been resumed in the child process after fork (see |
625 | C<ev_fork>). |
777 | C<ev_fork>). |
626 | |
778 | |
|
|
779 | =item C<EV_ASYNC> |
|
|
780 | |
|
|
781 | The given async watcher has been asynchronously notified (see C<ev_async>). |
|
|
782 | |
627 | =item C<EV_ERROR> |
783 | =item C<EV_ERROR> |
628 | |
784 | |
629 | An unspecified error has occured, the watcher has been stopped. This might |
785 | An unspecified error has occured, the watcher has been stopped. This might |
630 | happen because the watcher could not be properly started because libev |
786 | happen because the watcher could not be properly started because libev |
631 | ran out of memory, a file descriptor was found to be closed or any other |
787 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
702 | =item bool ev_is_pending (ev_TYPE *watcher) |
858 | =item bool ev_is_pending (ev_TYPE *watcher) |
703 | |
859 | |
704 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
860 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
705 | events but its callback has not yet been invoked). As long as a watcher |
861 | events but its callback has not yet been invoked). As long as a watcher |
706 | is pending (but not active) you must not call an init function on it (but |
862 | is pending (but not active) you must not call an init function on it (but |
707 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
863 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
708 | libev (e.g. you cnanot C<free ()> it). |
864 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
865 | it). |
709 | |
866 | |
710 | =item callback ev_cb (ev_TYPE *watcher) |
867 | =item callback ev_cb (ev_TYPE *watcher) |
711 | |
868 | |
712 | Returns the callback currently set on the watcher. |
869 | Returns the callback currently set on the watcher. |
713 | |
870 | |
714 | =item ev_cb_set (ev_TYPE *watcher, callback) |
871 | =item ev_cb_set (ev_TYPE *watcher, callback) |
715 | |
872 | |
716 | Change the callback. You can change the callback at virtually any time |
873 | Change the callback. You can change the callback at virtually any time |
717 | (modulo threads). |
874 | (modulo threads). |
|
|
875 | |
|
|
876 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
877 | |
|
|
878 | =item int ev_priority (ev_TYPE *watcher) |
|
|
879 | |
|
|
880 | Set and query the priority of the watcher. The priority is a small |
|
|
881 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
882 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
883 | before watchers with lower priority, but priority will not keep watchers |
|
|
884 | from being executed (except for C<ev_idle> watchers). |
|
|
885 | |
|
|
886 | This means that priorities are I<only> used for ordering callback |
|
|
887 | invocation after new events have been received. This is useful, for |
|
|
888 | example, to reduce latency after idling, or more often, to bind two |
|
|
889 | watchers on the same event and make sure one is called first. |
|
|
890 | |
|
|
891 | If you need to suppress invocation when higher priority events are pending |
|
|
892 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
893 | |
|
|
894 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
895 | pending. |
|
|
896 | |
|
|
897 | The default priority used by watchers when no priority has been set is |
|
|
898 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
899 | |
|
|
900 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
901 | fine, as long as you do not mind that the priority value you query might |
|
|
902 | or might not have been adjusted to be within valid range. |
|
|
903 | |
|
|
904 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
905 | |
|
|
906 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
907 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
908 | can deal with that fact. |
|
|
909 | |
|
|
910 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
911 | |
|
|
912 | If the watcher is pending, this function returns clears its pending status |
|
|
913 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
914 | watcher isn't pending it does nothing and returns C<0>. |
718 | |
915 | |
719 | =back |
916 | =back |
720 | |
917 | |
721 | |
918 | |
722 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
919 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
807 | In general you can register as many read and/or write event watchers per |
1004 | In general you can register as many read and/or write event watchers per |
808 | fd as you want (as long as you don't confuse yourself). Setting all file |
1005 | fd as you want (as long as you don't confuse yourself). Setting all file |
809 | descriptors to non-blocking mode is also usually a good idea (but not |
1006 | descriptors to non-blocking mode is also usually a good idea (but not |
810 | required if you know what you are doing). |
1007 | required if you know what you are doing). |
811 | |
1008 | |
812 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
813 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
814 | descriptors correctly if you register interest in two or more fds pointing |
|
|
815 | to the same underlying file/socket/etc. description (that is, they share |
|
|
816 | the same underlying "file open"). |
|
|
817 | |
|
|
818 | If you must do this, then force the use of a known-to-be-good backend |
1009 | If you must do this, then force the use of a known-to-be-good backend |
819 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1010 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
820 | C<EVBACKEND_POLL>). |
1011 | C<EVBACKEND_POLL>). |
821 | |
1012 | |
822 | Another thing you have to watch out for is that it is quite easy to |
1013 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
828 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1019 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
829 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1020 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
830 | |
1021 | |
831 | If you cannot run the fd in non-blocking mode (for example you should not |
1022 | If you cannot run the fd in non-blocking mode (for example you should not |
832 | play around with an Xlib connection), then you have to seperately re-test |
1023 | play around with an Xlib connection), then you have to seperately re-test |
833 | wether a file descriptor is really ready with a known-to-be good interface |
1024 | whether a file descriptor is really ready with a known-to-be good interface |
834 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1025 | such as poll (fortunately in our Xlib example, Xlib already does this on |
835 | its own, so its quite safe to use). |
1026 | its own, so its quite safe to use). |
|
|
1027 | |
|
|
1028 | =head3 The special problem of disappearing file descriptors |
|
|
1029 | |
|
|
1030 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1031 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1032 | such as C<dup>). The reason is that you register interest in some file |
|
|
1033 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1034 | this interest. If another file descriptor with the same number then is |
|
|
1035 | registered with libev, there is no efficient way to see that this is, in |
|
|
1036 | fact, a different file descriptor. |
|
|
1037 | |
|
|
1038 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1039 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1040 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1041 | it is assumed that the file descriptor stays the same. That means that |
|
|
1042 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1043 | descriptor even if the file descriptor number itself did not change. |
|
|
1044 | |
|
|
1045 | This is how one would do it normally anyway, the important point is that |
|
|
1046 | the libev application should not optimise around libev but should leave |
|
|
1047 | optimisations to libev. |
|
|
1048 | |
|
|
1049 | =head3 The special problem of dup'ed file descriptors |
|
|
1050 | |
|
|
1051 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1052 | but only events for the underlying file descriptions. That means when you |
|
|
1053 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1054 | events for them, only one file descriptor might actually receive events. |
|
|
1055 | |
|
|
1056 | There is no workaround possible except not registering events |
|
|
1057 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1058 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1059 | |
|
|
1060 | =head3 The special problem of fork |
|
|
1061 | |
|
|
1062 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1063 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1064 | it in the child. |
|
|
1065 | |
|
|
1066 | To support fork in your programs, you either have to call |
|
|
1067 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1068 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1069 | C<EVBACKEND_POLL>. |
|
|
1070 | |
|
|
1071 | |
|
|
1072 | =head3 Watcher-Specific Functions |
836 | |
1073 | |
837 | =over 4 |
1074 | =over 4 |
838 | |
1075 | |
839 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1076 | =item ev_io_init (ev_io *, callback, int fd, int events) |
840 | |
1077 | |
… | |
… | |
851 | =item int events [read-only] |
1088 | =item int events [read-only] |
852 | |
1089 | |
853 | The events being watched. |
1090 | The events being watched. |
854 | |
1091 | |
855 | =back |
1092 | =back |
|
|
1093 | |
|
|
1094 | =head3 Examples |
856 | |
1095 | |
857 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1096 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
858 | readable, but only once. Since it is likely line-buffered, you could |
1097 | readable, but only once. Since it is likely line-buffered, you could |
859 | attempt to read a whole line in the callback. |
1098 | attempt to read a whole line in the callback. |
860 | |
1099 | |
… | |
… | |
894 | |
1133 | |
895 | The callback is guarenteed to be invoked only when its timeout has passed, |
1134 | The callback is guarenteed to be invoked only when its timeout has passed, |
896 | but if multiple timers become ready during the same loop iteration then |
1135 | but if multiple timers become ready during the same loop iteration then |
897 | order of execution is undefined. |
1136 | order of execution is undefined. |
898 | |
1137 | |
|
|
1138 | =head3 Watcher-Specific Functions and Data Members |
|
|
1139 | |
899 | =over 4 |
1140 | =over 4 |
900 | |
1141 | |
901 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1142 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
902 | |
1143 | |
903 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1144 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
916 | =item ev_timer_again (loop) |
1157 | =item ev_timer_again (loop) |
917 | |
1158 | |
918 | This will act as if the timer timed out and restart it again if it is |
1159 | This will act as if the timer timed out and restart it again if it is |
919 | repeating. The exact semantics are: |
1160 | repeating. The exact semantics are: |
920 | |
1161 | |
|
|
1162 | If the timer is pending, its pending status is cleared. |
|
|
1163 | |
921 | If the timer is started but nonrepeating, stop it. |
1164 | If the timer is started but nonrepeating, stop it (as if it timed out). |
922 | |
1165 | |
923 | If the timer is repeating, either start it if necessary (with the repeat |
1166 | If the timer is repeating, either start it if necessary (with the |
924 | value), or reset the running timer to the repeat value. |
1167 | C<repeat> value), or reset the running timer to the C<repeat> value. |
925 | |
1168 | |
926 | This sounds a bit complicated, but here is a useful and typical |
1169 | This sounds a bit complicated, but here is a useful and typical |
927 | example: Imagine you have a tcp connection and you want a so-called |
1170 | example: Imagine you have a tcp connection and you want a so-called idle |
928 | idle timeout, that is, you want to be called when there have been, |
1171 | timeout, that is, you want to be called when there have been, say, 60 |
929 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1172 | seconds of inactivity on the socket. The easiest way to do this is to |
930 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1173 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
931 | C<ev_timer_again> each time you successfully read or write some data. If |
1174 | C<ev_timer_again> each time you successfully read or write some data. If |
932 | you go into an idle state where you do not expect data to travel on the |
1175 | you go into an idle state where you do not expect data to travel on the |
933 | socket, you can stop the timer, and again will automatically restart it if |
1176 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
934 | need be. |
1177 | automatically restart it if need be. |
935 | |
1178 | |
936 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1179 | That means you can ignore the C<after> value and C<ev_timer_start> |
937 | and only ever use the C<repeat> value: |
1180 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
938 | |
1181 | |
939 | ev_timer_init (timer, callback, 0., 5.); |
1182 | ev_timer_init (timer, callback, 0., 5.); |
940 | ev_timer_again (loop, timer); |
1183 | ev_timer_again (loop, timer); |
941 | ... |
1184 | ... |
942 | timer->again = 17.; |
1185 | timer->again = 17.; |
943 | ev_timer_again (loop, timer); |
1186 | ev_timer_again (loop, timer); |
944 | ... |
1187 | ... |
945 | timer->again = 10.; |
1188 | timer->again = 10.; |
946 | ev_timer_again (loop, timer); |
1189 | ev_timer_again (loop, timer); |
947 | |
1190 | |
948 | This is more efficient then stopping/starting the timer eahc time you want |
1191 | This is more slightly efficient then stopping/starting the timer each time |
949 | to modify its timeout value. |
1192 | you want to modify its timeout value. |
950 | |
1193 | |
951 | =item ev_tstamp repeat [read-write] |
1194 | =item ev_tstamp repeat [read-write] |
952 | |
1195 | |
953 | The current C<repeat> value. Will be used each time the watcher times out |
1196 | The current C<repeat> value. Will be used each time the watcher times out |
954 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1197 | or C<ev_timer_again> is called and determines the next timeout (if any), |
955 | which is also when any modifications are taken into account. |
1198 | which is also when any modifications are taken into account. |
956 | |
1199 | |
957 | =back |
1200 | =back |
|
|
1201 | |
|
|
1202 | =head3 Examples |
958 | |
1203 | |
959 | Example: Create a timer that fires after 60 seconds. |
1204 | Example: Create a timer that fires after 60 seconds. |
960 | |
1205 | |
961 | static void |
1206 | static void |
962 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1207 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
… | |
… | |
996 | but on wallclock time (absolute time). You can tell a periodic watcher |
1241 | but on wallclock time (absolute time). You can tell a periodic watcher |
997 | to trigger "at" some specific point in time. For example, if you tell a |
1242 | to trigger "at" some specific point in time. For example, if you tell a |
998 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1243 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
999 | + 10.>) and then reset your system clock to the last year, then it will |
1244 | + 10.>) and then reset your system clock to the last year, then it will |
1000 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1245 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1001 | roughly 10 seconds later and of course not if you reset your system time |
1246 | roughly 10 seconds later). |
1002 | again). |
|
|
1003 | |
1247 | |
1004 | They can also be used to implement vastly more complex timers, such as |
1248 | They can also be used to implement vastly more complex timers, such as |
1005 | triggering an event on eahc midnight, local time. |
1249 | triggering an event on each midnight, local time or other, complicated, |
|
|
1250 | rules. |
1006 | |
1251 | |
1007 | As with timers, the callback is guarenteed to be invoked only when the |
1252 | As with timers, the callback is guarenteed to be invoked only when the |
1008 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1253 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1009 | during the same loop iteration then order of execution is undefined. |
1254 | during the same loop iteration then order of execution is undefined. |
1010 | |
1255 | |
|
|
1256 | =head3 Watcher-Specific Functions and Data Members |
|
|
1257 | |
1011 | =over 4 |
1258 | =over 4 |
1012 | |
1259 | |
1013 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1260 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1014 | |
1261 | |
1015 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1262 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1017 | Lots of arguments, lets sort it out... There are basically three modes of |
1264 | Lots of arguments, lets sort it out... There are basically three modes of |
1018 | operation, and we will explain them from simplest to complex: |
1265 | operation, and we will explain them from simplest to complex: |
1019 | |
1266 | |
1020 | =over 4 |
1267 | =over 4 |
1021 | |
1268 | |
1022 | =item * absolute timer (interval = reschedule_cb = 0) |
1269 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1023 | |
1270 | |
1024 | In this configuration the watcher triggers an event at the wallclock time |
1271 | In this configuration the watcher triggers an event at the wallclock time |
1025 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1272 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1026 | that is, if it is to be run at January 1st 2011 then it will run when the |
1273 | that is, if it is to be run at January 1st 2011 then it will run when the |
1027 | system time reaches or surpasses this time. |
1274 | system time reaches or surpasses this time. |
1028 | |
1275 | |
1029 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1276 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1030 | |
1277 | |
1031 | In this mode the watcher will always be scheduled to time out at the next |
1278 | In this mode the watcher will always be scheduled to time out at the next |
1032 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1279 | C<at + N * interval> time (for some integer N, which can also be negative) |
1033 | of any time jumps. |
1280 | and then repeat, regardless of any time jumps. |
1034 | |
1281 | |
1035 | This can be used to create timers that do not drift with respect to system |
1282 | This can be used to create timers that do not drift with respect to system |
1036 | time: |
1283 | time: |
1037 | |
1284 | |
1038 | ev_periodic_set (&periodic, 0., 3600., 0); |
1285 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1044 | |
1291 | |
1045 | Another way to think about it (for the mathematically inclined) is that |
1292 | Another way to think about it (for the mathematically inclined) is that |
1046 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1293 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1047 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1294 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1048 | |
1295 | |
|
|
1296 | For numerical stability it is preferable that the C<at> value is near |
|
|
1297 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1298 | this value. |
|
|
1299 | |
1049 | =item * manual reschedule mode (reschedule_cb = callback) |
1300 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1050 | |
1301 | |
1051 | In this mode the values for C<interval> and C<at> are both being |
1302 | In this mode the values for C<interval> and C<at> are both being |
1052 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1303 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1053 | reschedule callback will be called with the watcher as first, and the |
1304 | reschedule callback will be called with the watcher as first, and the |
1054 | current time as second argument. |
1305 | current time as second argument. |
1055 | |
1306 | |
1056 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1307 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1057 | ever, or make any event loop modifications>. If you need to stop it, |
1308 | ever, or make any event loop modifications>. If you need to stop it, |
1058 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1309 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1059 | starting a prepare watcher). |
1310 | starting an C<ev_prepare> watcher, which is legal). |
1060 | |
1311 | |
1061 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1312 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1062 | ev_tstamp now)>, e.g.: |
1313 | ev_tstamp now)>, e.g.: |
1063 | |
1314 | |
1064 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1315 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1087 | Simply stops and restarts the periodic watcher again. This is only useful |
1338 | Simply stops and restarts the periodic watcher again. This is only useful |
1088 | when you changed some parameters or the reschedule callback would return |
1339 | when you changed some parameters or the reschedule callback would return |
1089 | a different time than the last time it was called (e.g. in a crond like |
1340 | a different time than the last time it was called (e.g. in a crond like |
1090 | program when the crontabs have changed). |
1341 | program when the crontabs have changed). |
1091 | |
1342 | |
|
|
1343 | =item ev_tstamp offset [read-write] |
|
|
1344 | |
|
|
1345 | When repeating, this contains the offset value, otherwise this is the |
|
|
1346 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1347 | |
|
|
1348 | Can be modified any time, but changes only take effect when the periodic |
|
|
1349 | timer fires or C<ev_periodic_again> is being called. |
|
|
1350 | |
1092 | =item ev_tstamp interval [read-write] |
1351 | =item ev_tstamp interval [read-write] |
1093 | |
1352 | |
1094 | The current interval value. Can be modified any time, but changes only |
1353 | The current interval value. Can be modified any time, but changes only |
1095 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1354 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1096 | called. |
1355 | called. |
… | |
… | |
1099 | |
1358 | |
1100 | The current reschedule callback, or C<0>, if this functionality is |
1359 | The current reschedule callback, or C<0>, if this functionality is |
1101 | switched off. Can be changed any time, but changes only take effect when |
1360 | switched off. Can be changed any time, but changes only take effect when |
1102 | the periodic timer fires or C<ev_periodic_again> is being called. |
1361 | the periodic timer fires or C<ev_periodic_again> is being called. |
1103 | |
1362 | |
|
|
1363 | =item ev_tstamp at [read-only] |
|
|
1364 | |
|
|
1365 | When active, contains the absolute time that the watcher is supposed to |
|
|
1366 | trigger next. |
|
|
1367 | |
1104 | =back |
1368 | =back |
|
|
1369 | |
|
|
1370 | =head3 Examples |
1105 | |
1371 | |
1106 | Example: Call a callback every hour, or, more precisely, whenever the |
1372 | Example: Call a callback every hour, or, more precisely, whenever the |
1107 | system clock is divisible by 3600. The callback invocation times have |
1373 | system clock is divisible by 3600. The callback invocation times have |
1108 | potentially a lot of jittering, but good long-term stability. |
1374 | potentially a lot of jittering, but good long-term stability. |
1109 | |
1375 | |
… | |
… | |
1149 | with the kernel (thus it coexists with your own signal handlers as long |
1415 | with the kernel (thus it coexists with your own signal handlers as long |
1150 | as you don't register any with libev). Similarly, when the last signal |
1416 | as you don't register any with libev). Similarly, when the last signal |
1151 | watcher for a signal is stopped libev will reset the signal handler to |
1417 | watcher for a signal is stopped libev will reset the signal handler to |
1152 | SIG_DFL (regardless of what it was set to before). |
1418 | SIG_DFL (regardless of what it was set to before). |
1153 | |
1419 | |
|
|
1420 | =head3 Watcher-Specific Functions and Data Members |
|
|
1421 | |
1154 | =over 4 |
1422 | =over 4 |
1155 | |
1423 | |
1156 | =item ev_signal_init (ev_signal *, callback, int signum) |
1424 | =item ev_signal_init (ev_signal *, callback, int signum) |
1157 | |
1425 | |
1158 | =item ev_signal_set (ev_signal *, int signum) |
1426 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1170 | =head2 C<ev_child> - watch out for process status changes |
1438 | =head2 C<ev_child> - watch out for process status changes |
1171 | |
1439 | |
1172 | Child watchers trigger when your process receives a SIGCHLD in response to |
1440 | Child watchers trigger when your process receives a SIGCHLD in response to |
1173 | some child status changes (most typically when a child of yours dies). |
1441 | some child status changes (most typically when a child of yours dies). |
1174 | |
1442 | |
|
|
1443 | =head3 Watcher-Specific Functions and Data Members |
|
|
1444 | |
1175 | =over 4 |
1445 | =over 4 |
1176 | |
1446 | |
1177 | =item ev_child_init (ev_child *, callback, int pid) |
1447 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1178 | |
1448 | |
1179 | =item ev_child_set (ev_child *, int pid) |
1449 | =item ev_child_set (ev_child *, int pid, int trace) |
1180 | |
1450 | |
1181 | Configures the watcher to wait for status changes of process C<pid> (or |
1451 | Configures the watcher to wait for status changes of process C<pid> (or |
1182 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1452 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1183 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1453 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1184 | the status word (use the macros from C<sys/wait.h> and see your systems |
1454 | the status word (use the macros from C<sys/wait.h> and see your systems |
1185 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1455 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1186 | process causing the status change. |
1456 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1457 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1458 | activate the watcher when the process is stopped or continued). |
1187 | |
1459 | |
1188 | =item int pid [read-only] |
1460 | =item int pid [read-only] |
1189 | |
1461 | |
1190 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1462 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1191 | |
1463 | |
… | |
… | |
1197 | |
1469 | |
1198 | The process exit/trace status caused by C<rpid> (see your systems |
1470 | The process exit/trace status caused by C<rpid> (see your systems |
1199 | C<waitpid> and C<sys/wait.h> documentation for details). |
1471 | C<waitpid> and C<sys/wait.h> documentation for details). |
1200 | |
1472 | |
1201 | =back |
1473 | =back |
|
|
1474 | |
|
|
1475 | =head3 Examples |
1202 | |
1476 | |
1203 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1477 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1204 | |
1478 | |
1205 | static void |
1479 | static void |
1206 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1480 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1247 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1521 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1248 | to fall back to regular polling again even with inotify, but changes are |
1522 | to fall back to regular polling again even with inotify, but changes are |
1249 | usually detected immediately, and if the file exists there will be no |
1523 | usually detected immediately, and if the file exists there will be no |
1250 | polling. |
1524 | polling. |
1251 | |
1525 | |
|
|
1526 | =head3 Inotify |
|
|
1527 | |
|
|
1528 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1529 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1530 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1531 | when the first C<ev_stat> watcher is being started. |
|
|
1532 | |
|
|
1533 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1534 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1535 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1536 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1537 | |
|
|
1538 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1539 | implement this functionality, due to the requirement of having a file |
|
|
1540 | descriptor open on the object at all times). |
|
|
1541 | |
|
|
1542 | =head3 The special problem of stat time resolution |
|
|
1543 | |
|
|
1544 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1545 | even on systems where the resolution is higher, many filesystems still |
|
|
1546 | only support whole seconds. |
|
|
1547 | |
|
|
1548 | That means that, if the time is the only thing that changes, you might |
|
|
1549 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1550 | your callback, which does something. When there is another update within |
|
|
1551 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1552 | |
|
|
1553 | The solution to this is to delay acting on a change for a second (or till |
|
|
1554 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1555 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1556 | is added to work around small timing inconsistencies of some operating |
|
|
1557 | systems. |
|
|
1558 | |
|
|
1559 | =head3 Watcher-Specific Functions and Data Members |
|
|
1560 | |
1252 | =over 4 |
1561 | =over 4 |
1253 | |
1562 | |
1254 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1563 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1255 | |
1564 | |
1256 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
1565 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
… | |
… | |
1291 | =item const char *path [read-only] |
1600 | =item const char *path [read-only] |
1292 | |
1601 | |
1293 | The filesystem path that is being watched. |
1602 | The filesystem path that is being watched. |
1294 | |
1603 | |
1295 | =back |
1604 | =back |
|
|
1605 | |
|
|
1606 | =head3 Examples |
1296 | |
1607 | |
1297 | Example: Watch C</etc/passwd> for attribute changes. |
1608 | Example: Watch C</etc/passwd> for attribute changes. |
1298 | |
1609 | |
1299 | static void |
1610 | static void |
1300 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1611 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1313 | } |
1624 | } |
1314 | |
1625 | |
1315 | ... |
1626 | ... |
1316 | ev_stat passwd; |
1627 | ev_stat passwd; |
1317 | |
1628 | |
1318 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1629 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1319 | ev_stat_start (loop, &passwd); |
1630 | ev_stat_start (loop, &passwd); |
1320 | |
1631 | |
|
|
1632 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1633 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1634 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1635 | C<ev_timer> callback invocation). |
|
|
1636 | |
|
|
1637 | static ev_stat passwd; |
|
|
1638 | static ev_timer timer; |
|
|
1639 | |
|
|
1640 | static void |
|
|
1641 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1642 | { |
|
|
1643 | ev_timer_stop (EV_A_ w); |
|
|
1644 | |
|
|
1645 | /* now it's one second after the most recent passwd change */ |
|
|
1646 | } |
|
|
1647 | |
|
|
1648 | static void |
|
|
1649 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1650 | { |
|
|
1651 | /* reset the one-second timer */ |
|
|
1652 | ev_timer_again (EV_A_ &timer); |
|
|
1653 | } |
|
|
1654 | |
|
|
1655 | ... |
|
|
1656 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1657 | ev_stat_start (loop, &passwd); |
|
|
1658 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1659 | |
1321 | |
1660 | |
1322 | =head2 C<ev_idle> - when you've got nothing better to do... |
1661 | =head2 C<ev_idle> - when you've got nothing better to do... |
1323 | |
1662 | |
1324 | Idle watchers trigger events when there are no other events are pending |
1663 | Idle watchers trigger events when no other events of the same or higher |
1325 | (prepare, check and other idle watchers do not count). That is, as long |
1664 | priority are pending (prepare, check and other idle watchers do not |
1326 | as your process is busy handling sockets or timeouts (or even signals, |
1665 | count). |
1327 | imagine) it will not be triggered. But when your process is idle all idle |
1666 | |
1328 | watchers are being called again and again, once per event loop iteration - |
1667 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1668 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1669 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1670 | are pending), the idle watchers are being called once per event loop |
1329 | until stopped, that is, or your process receives more events and becomes |
1671 | iteration - until stopped, that is, or your process receives more events |
1330 | busy. |
1672 | and becomes busy again with higher priority stuff. |
1331 | |
1673 | |
1332 | The most noteworthy effect is that as long as any idle watchers are |
1674 | The most noteworthy effect is that as long as any idle watchers are |
1333 | active, the process will not block when waiting for new events. |
1675 | active, the process will not block when waiting for new events. |
1334 | |
1676 | |
1335 | Apart from keeping your process non-blocking (which is a useful |
1677 | Apart from keeping your process non-blocking (which is a useful |
1336 | effect on its own sometimes), idle watchers are a good place to do |
1678 | effect on its own sometimes), idle watchers are a good place to do |
1337 | "pseudo-background processing", or delay processing stuff to after the |
1679 | "pseudo-background processing", or delay processing stuff to after the |
1338 | event loop has handled all outstanding events. |
1680 | event loop has handled all outstanding events. |
1339 | |
1681 | |
|
|
1682 | =head3 Watcher-Specific Functions and Data Members |
|
|
1683 | |
1340 | =over 4 |
1684 | =over 4 |
1341 | |
1685 | |
1342 | =item ev_idle_init (ev_signal *, callback) |
1686 | =item ev_idle_init (ev_signal *, callback) |
1343 | |
1687 | |
1344 | Initialises and configures the idle watcher - it has no parameters of any |
1688 | Initialises and configures the idle watcher - it has no parameters of any |
1345 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1689 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1346 | believe me. |
1690 | believe me. |
1347 | |
1691 | |
1348 | =back |
1692 | =back |
|
|
1693 | |
|
|
1694 | =head3 Examples |
1349 | |
1695 | |
1350 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1696 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1351 | callback, free it. Also, use no error checking, as usual. |
1697 | callback, free it. Also, use no error checking, as usual. |
1352 | |
1698 | |
1353 | static void |
1699 | static void |
1354 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1700 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1355 | { |
1701 | { |
1356 | free (w); |
1702 | free (w); |
1357 | // now do something you wanted to do when the program has |
1703 | // now do something you wanted to do when the program has |
1358 | // no longer asnything immediate to do. |
1704 | // no longer anything immediate to do. |
1359 | } |
1705 | } |
1360 | |
1706 | |
1361 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1707 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1362 | ev_idle_init (idle_watcher, idle_cb); |
1708 | ev_idle_init (idle_watcher, idle_cb); |
1363 | ev_idle_start (loop, idle_cb); |
1709 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1401 | with priority higher than or equal to the event loop and one coroutine |
1747 | with priority higher than or equal to the event loop and one coroutine |
1402 | of lower priority, but only once, using idle watchers to keep the event |
1748 | of lower priority, but only once, using idle watchers to keep the event |
1403 | loop from blocking if lower-priority coroutines are active, thus mapping |
1749 | loop from blocking if lower-priority coroutines are active, thus mapping |
1404 | low-priority coroutines to idle/background tasks). |
1750 | low-priority coroutines to idle/background tasks). |
1405 | |
1751 | |
|
|
1752 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1753 | priority, to ensure that they are being run before any other watchers |
|
|
1754 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1755 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1756 | supports this, they will be called before other C<ev_check> watchers |
|
|
1757 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1758 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1759 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1760 | coexist peacefully with others). |
|
|
1761 | |
|
|
1762 | =head3 Watcher-Specific Functions and Data Members |
|
|
1763 | |
1406 | =over 4 |
1764 | =over 4 |
1407 | |
1765 | |
1408 | =item ev_prepare_init (ev_prepare *, callback) |
1766 | =item ev_prepare_init (ev_prepare *, callback) |
1409 | |
1767 | |
1410 | =item ev_check_init (ev_check *, callback) |
1768 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1413 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1771 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1414 | macros, but using them is utterly, utterly and completely pointless. |
1772 | macros, but using them is utterly, utterly and completely pointless. |
1415 | |
1773 | |
1416 | =back |
1774 | =back |
1417 | |
1775 | |
1418 | Example: To include a library such as adns, you would add IO watchers |
1776 | =head3 Examples |
1419 | and a timeout watcher in a prepare handler, as required by libadns, and |
1777 | |
|
|
1778 | There are a number of principal ways to embed other event loops or modules |
|
|
1779 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1780 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1781 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1782 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1783 | into the Glib event loop). |
|
|
1784 | |
|
|
1785 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1420 | in a check watcher, destroy them and call into libadns. What follows is |
1786 | and in a check watcher, destroy them and call into libadns. What follows |
1421 | pseudo-code only of course: |
1787 | is pseudo-code only of course. This requires you to either use a low |
|
|
1788 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1789 | the callbacks for the IO/timeout watchers might not have been called yet. |
1422 | |
1790 | |
1423 | static ev_io iow [nfd]; |
1791 | static ev_io iow [nfd]; |
1424 | static ev_timer tw; |
1792 | static ev_timer tw; |
1425 | |
1793 | |
1426 | static void |
1794 | static void |
1427 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1795 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1428 | { |
1796 | { |
1429 | // set the relevant poll flags |
|
|
1430 | // could also call adns_processreadable etc. here |
|
|
1431 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1432 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1433 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1434 | } |
1797 | } |
1435 | |
1798 | |
1436 | // create io watchers for each fd and a timer before blocking |
1799 | // create io watchers for each fd and a timer before blocking |
1437 | static void |
1800 | static void |
1438 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1801 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1439 | { |
1802 | { |
1440 | int timeout = 3600000;truct pollfd fds [nfd]; |
1803 | int timeout = 3600000; |
|
|
1804 | struct pollfd fds [nfd]; |
1441 | // actual code will need to loop here and realloc etc. |
1805 | // actual code will need to loop here and realloc etc. |
1442 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1806 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1443 | |
1807 | |
1444 | /* the callback is illegal, but won't be called as we stop during check */ |
1808 | /* the callback is illegal, but won't be called as we stop during check */ |
1445 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1809 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1446 | ev_timer_start (loop, &tw); |
1810 | ev_timer_start (loop, &tw); |
1447 | |
1811 | |
1448 | // create on ev_io per pollfd |
1812 | // create one ev_io per pollfd |
1449 | for (int i = 0; i < nfd; ++i) |
1813 | for (int i = 0; i < nfd; ++i) |
1450 | { |
1814 | { |
1451 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1815 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1452 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1816 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1453 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1817 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1454 | |
1818 | |
1455 | fds [i].revents = 0; |
1819 | fds [i].revents = 0; |
1456 | iow [i].data = fds + i; |
|
|
1457 | ev_io_start (loop, iow + i); |
1820 | ev_io_start (loop, iow + i); |
1458 | } |
1821 | } |
1459 | } |
1822 | } |
1460 | |
1823 | |
1461 | // stop all watchers after blocking |
1824 | // stop all watchers after blocking |
… | |
… | |
1463 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1826 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1464 | { |
1827 | { |
1465 | ev_timer_stop (loop, &tw); |
1828 | ev_timer_stop (loop, &tw); |
1466 | |
1829 | |
1467 | for (int i = 0; i < nfd; ++i) |
1830 | for (int i = 0; i < nfd; ++i) |
|
|
1831 | { |
|
|
1832 | // set the relevant poll flags |
|
|
1833 | // could also call adns_processreadable etc. here |
|
|
1834 | struct pollfd *fd = fds + i; |
|
|
1835 | int revents = ev_clear_pending (iow + i); |
|
|
1836 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1837 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1838 | |
|
|
1839 | // now stop the watcher |
1468 | ev_io_stop (loop, iow + i); |
1840 | ev_io_stop (loop, iow + i); |
|
|
1841 | } |
1469 | |
1842 | |
1470 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1843 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1844 | } |
|
|
1845 | |
|
|
1846 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1847 | in the prepare watcher and would dispose of the check watcher. |
|
|
1848 | |
|
|
1849 | Method 3: If the module to be embedded supports explicit event |
|
|
1850 | notification (adns does), you can also make use of the actual watcher |
|
|
1851 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1852 | |
|
|
1853 | static void |
|
|
1854 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1855 | { |
|
|
1856 | adns_state ads = (adns_state)w->data; |
|
|
1857 | update_now (EV_A); |
|
|
1858 | |
|
|
1859 | adns_processtimeouts (ads, &tv_now); |
|
|
1860 | } |
|
|
1861 | |
|
|
1862 | static void |
|
|
1863 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1864 | { |
|
|
1865 | adns_state ads = (adns_state)w->data; |
|
|
1866 | update_now (EV_A); |
|
|
1867 | |
|
|
1868 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1869 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1870 | } |
|
|
1871 | |
|
|
1872 | // do not ever call adns_afterpoll |
|
|
1873 | |
|
|
1874 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1875 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1876 | their poll function. The drawback with this solution is that the main |
|
|
1877 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1878 | this. |
|
|
1879 | |
|
|
1880 | static gint |
|
|
1881 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1882 | { |
|
|
1883 | int got_events = 0; |
|
|
1884 | |
|
|
1885 | for (n = 0; n < nfds; ++n) |
|
|
1886 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1887 | |
|
|
1888 | if (timeout >= 0) |
|
|
1889 | // create/start timer |
|
|
1890 | |
|
|
1891 | // poll |
|
|
1892 | ev_loop (EV_A_ 0); |
|
|
1893 | |
|
|
1894 | // stop timer again |
|
|
1895 | if (timeout >= 0) |
|
|
1896 | ev_timer_stop (EV_A_ &to); |
|
|
1897 | |
|
|
1898 | // stop io watchers again - their callbacks should have set |
|
|
1899 | for (n = 0; n < nfds; ++n) |
|
|
1900 | ev_io_stop (EV_A_ iow [n]); |
|
|
1901 | |
|
|
1902 | return got_events; |
1471 | } |
1903 | } |
1472 | |
1904 | |
1473 | |
1905 | |
1474 | =head2 C<ev_embed> - when one backend isn't enough... |
1906 | =head2 C<ev_embed> - when one backend isn't enough... |
1475 | |
1907 | |
… | |
… | |
1518 | portable one. |
1950 | portable one. |
1519 | |
1951 | |
1520 | So when you want to use this feature you will always have to be prepared |
1952 | So when you want to use this feature you will always have to be prepared |
1521 | that you cannot get an embeddable loop. The recommended way to get around |
1953 | that you cannot get an embeddable loop. The recommended way to get around |
1522 | this is to have a separate variables for your embeddable loop, try to |
1954 | this is to have a separate variables for your embeddable loop, try to |
1523 | create it, and if that fails, use the normal loop for everything: |
1955 | create it, and if that fails, use the normal loop for everything. |
|
|
1956 | |
|
|
1957 | =head3 Watcher-Specific Functions and Data Members |
|
|
1958 | |
|
|
1959 | =over 4 |
|
|
1960 | |
|
|
1961 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1962 | |
|
|
1963 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1964 | |
|
|
1965 | Configures the watcher to embed the given loop, which must be |
|
|
1966 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1967 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1968 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1969 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1970 | |
|
|
1971 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1972 | |
|
|
1973 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1974 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1975 | apropriate way for embedded loops. |
|
|
1976 | |
|
|
1977 | =item struct ev_loop *other [read-only] |
|
|
1978 | |
|
|
1979 | The embedded event loop. |
|
|
1980 | |
|
|
1981 | =back |
|
|
1982 | |
|
|
1983 | =head3 Examples |
|
|
1984 | |
|
|
1985 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1986 | event loop. If that is not possible, use the default loop. The default |
|
|
1987 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1988 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1989 | used). |
1524 | |
1990 | |
1525 | struct ev_loop *loop_hi = ev_default_init (0); |
1991 | struct ev_loop *loop_hi = ev_default_init (0); |
1526 | struct ev_loop *loop_lo = 0; |
1992 | struct ev_loop *loop_lo = 0; |
1527 | struct ev_embed embed; |
1993 | struct ev_embed embed; |
1528 | |
1994 | |
… | |
… | |
1539 | ev_embed_start (loop_hi, &embed); |
2005 | ev_embed_start (loop_hi, &embed); |
1540 | } |
2006 | } |
1541 | else |
2007 | else |
1542 | loop_lo = loop_hi; |
2008 | loop_lo = loop_hi; |
1543 | |
2009 | |
1544 | =over 4 |
2010 | Example: Check if kqueue is available but not recommended and create |
|
|
2011 | a kqueue backend for use with sockets (which usually work with any |
|
|
2012 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2013 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1545 | |
2014 | |
1546 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2015 | struct ev_loop *loop = ev_default_init (0); |
|
|
2016 | struct ev_loop *loop_socket = 0; |
|
|
2017 | struct ev_embed embed; |
|
|
2018 | |
|
|
2019 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2020 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2021 | { |
|
|
2022 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2023 | ev_embed_start (loop, &embed); |
|
|
2024 | } |
1547 | |
2025 | |
1548 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2026 | if (!loop_socket) |
|
|
2027 | loop_socket = loop; |
1549 | |
2028 | |
1550 | Configures the watcher to embed the given loop, which must be |
2029 | // now use loop_socket for all sockets, and loop for everything else |
1551 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1552 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1553 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1554 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1555 | |
|
|
1556 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1557 | |
|
|
1558 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1559 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1560 | apropriate way for embedded loops. |
|
|
1561 | |
|
|
1562 | =item struct ev_loop *loop [read-only] |
|
|
1563 | |
|
|
1564 | The embedded event loop. |
|
|
1565 | |
|
|
1566 | =back |
|
|
1567 | |
2030 | |
1568 | |
2031 | |
1569 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2032 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1570 | |
2033 | |
1571 | Fork watchers are called when a C<fork ()> was detected (usually because |
2034 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1574 | event loop blocks next and before C<ev_check> watchers are being called, |
2037 | event loop blocks next and before C<ev_check> watchers are being called, |
1575 | and only in the child after the fork. If whoever good citizen calling |
2038 | and only in the child after the fork. If whoever good citizen calling |
1576 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2039 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1577 | handlers will be invoked, too, of course. |
2040 | handlers will be invoked, too, of course. |
1578 | |
2041 | |
|
|
2042 | =head3 Watcher-Specific Functions and Data Members |
|
|
2043 | |
1579 | =over 4 |
2044 | =over 4 |
1580 | |
2045 | |
1581 | =item ev_fork_init (ev_signal *, callback) |
2046 | =item ev_fork_init (ev_signal *, callback) |
1582 | |
2047 | |
1583 | Initialises and configures the fork watcher - it has no parameters of any |
2048 | Initialises and configures the fork watcher - it has no parameters of any |
1584 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
2049 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
1585 | believe me. |
2050 | believe me. |
|
|
2051 | |
|
|
2052 | =back |
|
|
2053 | |
|
|
2054 | |
|
|
2055 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2056 | |
|
|
2057 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2058 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2059 | loops - those are of course safe to use in different threads). |
|
|
2060 | |
|
|
2061 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2062 | control, for example because it belongs to another thread. This is what |
|
|
2063 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2064 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2065 | safe. |
|
|
2066 | |
|
|
2067 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2068 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2069 | (i.e. the number of callback invocations may be less than the number of |
|
|
2070 | C<ev_async_sent> calls). |
|
|
2071 | |
|
|
2072 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2073 | just the default loop. |
|
|
2074 | |
|
|
2075 | =head3 Queueing |
|
|
2076 | |
|
|
2077 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2078 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2079 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2080 | need elaborate support such as pthreads. |
|
|
2081 | |
|
|
2082 | That means that if you want to queue data, you have to provide your own |
|
|
2083 | queue. But at least I can tell you would implement locking around your |
|
|
2084 | queue: |
|
|
2085 | |
|
|
2086 | =over 4 |
|
|
2087 | |
|
|
2088 | =item queueing from a signal handler context |
|
|
2089 | |
|
|
2090 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2091 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2092 | some fictitiuous SIGUSR1 handler: |
|
|
2093 | |
|
|
2094 | static ev_async mysig; |
|
|
2095 | |
|
|
2096 | static void |
|
|
2097 | sigusr1_handler (void) |
|
|
2098 | { |
|
|
2099 | sometype data; |
|
|
2100 | |
|
|
2101 | // no locking etc. |
|
|
2102 | queue_put (data); |
|
|
2103 | ev_async_send (DEFAULT_ &mysig); |
|
|
2104 | } |
|
|
2105 | |
|
|
2106 | static void |
|
|
2107 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2108 | { |
|
|
2109 | sometype data; |
|
|
2110 | sigset_t block, prev; |
|
|
2111 | |
|
|
2112 | sigemptyset (&block); |
|
|
2113 | sigaddset (&block, SIGUSR1); |
|
|
2114 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2115 | |
|
|
2116 | while (queue_get (&data)) |
|
|
2117 | process (data); |
|
|
2118 | |
|
|
2119 | if (sigismember (&prev, SIGUSR1) |
|
|
2120 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2121 | } |
|
|
2122 | |
|
|
2123 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2124 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2125 | either...). |
|
|
2126 | |
|
|
2127 | =item queueing from a thread context |
|
|
2128 | |
|
|
2129 | The strategy for threads is different, as you cannot (easily) block |
|
|
2130 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2131 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2132 | |
|
|
2133 | static ev_async mysig; |
|
|
2134 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2135 | |
|
|
2136 | static void |
|
|
2137 | otherthread (void) |
|
|
2138 | { |
|
|
2139 | // only need to lock the actual queueing operation |
|
|
2140 | pthread_mutex_lock (&mymutex); |
|
|
2141 | queue_put (data); |
|
|
2142 | pthread_mutex_unlock (&mymutex); |
|
|
2143 | |
|
|
2144 | ev_async_send (DEFAULT_ &mysig); |
|
|
2145 | } |
|
|
2146 | |
|
|
2147 | static void |
|
|
2148 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2149 | { |
|
|
2150 | pthread_mutex_lock (&mymutex); |
|
|
2151 | |
|
|
2152 | while (queue_get (&data)) |
|
|
2153 | process (data); |
|
|
2154 | |
|
|
2155 | pthread_mutex_unlock (&mymutex); |
|
|
2156 | } |
|
|
2157 | |
|
|
2158 | =back |
|
|
2159 | |
|
|
2160 | |
|
|
2161 | =head3 Watcher-Specific Functions and Data Members |
|
|
2162 | |
|
|
2163 | =over 4 |
|
|
2164 | |
|
|
2165 | =item ev_async_init (ev_async *, callback) |
|
|
2166 | |
|
|
2167 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2168 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2169 | believe me. |
|
|
2170 | |
|
|
2171 | =item ev_async_send (loop, ev_async *) |
|
|
2172 | |
|
|
2173 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2174 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2175 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2176 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2177 | section below on what exactly this means). |
|
|
2178 | |
|
|
2179 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2180 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2181 | calls to C<ev_async_send>. |
1586 | |
2182 | |
1587 | =back |
2183 | =back |
1588 | |
2184 | |
1589 | |
2185 | |
1590 | =head1 OTHER FUNCTIONS |
2186 | =head1 OTHER FUNCTIONS |
… | |
… | |
1679 | |
2275 | |
1680 | To use it, |
2276 | To use it, |
1681 | |
2277 | |
1682 | #include <ev++.h> |
2278 | #include <ev++.h> |
1683 | |
2279 | |
1684 | (it is not installed by default). This automatically includes F<ev.h> |
2280 | This automatically includes F<ev.h> and puts all of its definitions (many |
1685 | and puts all of its definitions (many of them macros) into the global |
2281 | of them macros) into the global namespace. All C++ specific things are |
1686 | namespace. All C++ specific things are put into the C<ev> namespace. |
2282 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2283 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1687 | |
2284 | |
1688 | It should support all the same embedding options as F<ev.h>, most notably |
2285 | Care has been taken to keep the overhead low. The only data member the C++ |
1689 | C<EV_MULTIPLICITY>. |
2286 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2287 | that the watcher is associated with (or no additional members at all if |
|
|
2288 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2289 | |
|
|
2290 | Currently, functions, and static and non-static member functions can be |
|
|
2291 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2292 | need one additional pointer for context. If you need support for other |
|
|
2293 | types of functors please contact the author (preferably after implementing |
|
|
2294 | it). |
1690 | |
2295 | |
1691 | Here is a list of things available in the C<ev> namespace: |
2296 | Here is a list of things available in the C<ev> namespace: |
1692 | |
2297 | |
1693 | =over 4 |
2298 | =over 4 |
1694 | |
2299 | |
… | |
… | |
1710 | |
2315 | |
1711 | All of those classes have these methods: |
2316 | All of those classes have these methods: |
1712 | |
2317 | |
1713 | =over 4 |
2318 | =over 4 |
1714 | |
2319 | |
1715 | =item ev::TYPE::TYPE (object *, object::method *) |
2320 | =item ev::TYPE::TYPE () |
1716 | |
2321 | |
1717 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2322 | =item ev::TYPE::TYPE (struct ev_loop *) |
1718 | |
2323 | |
1719 | =item ev::TYPE::~TYPE |
2324 | =item ev::TYPE::~TYPE |
1720 | |
2325 | |
1721 | The constructor takes a pointer to an object and a method pointer to |
2326 | The constructor (optionally) takes an event loop to associate the watcher |
1722 | the event handler callback to call in this class. The constructor calls |
2327 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1723 | C<ev_init> for you, which means you have to call the C<set> method |
2328 | |
1724 | before starting it. If you do not specify a loop then the constructor |
2329 | The constructor calls C<ev_init> for you, which means you have to call the |
1725 | automatically associates the default loop with this watcher. |
2330 | C<set> method before starting it. |
|
|
2331 | |
|
|
2332 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2333 | method to set a callback before you can start the watcher. |
|
|
2334 | |
|
|
2335 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2336 | not allow explicit template arguments for constructors). |
1726 | |
2337 | |
1727 | The destructor automatically stops the watcher if it is active. |
2338 | The destructor automatically stops the watcher if it is active. |
|
|
2339 | |
|
|
2340 | =item w->set<class, &class::method> (object *) |
|
|
2341 | |
|
|
2342 | This method sets the callback method to call. The method has to have a |
|
|
2343 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2344 | first argument and the C<revents> as second. The object must be given as |
|
|
2345 | parameter and is stored in the C<data> member of the watcher. |
|
|
2346 | |
|
|
2347 | This method synthesizes efficient thunking code to call your method from |
|
|
2348 | the C callback that libev requires. If your compiler can inline your |
|
|
2349 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2350 | your compiler is good :), then the method will be fully inlined into the |
|
|
2351 | thunking function, making it as fast as a direct C callback. |
|
|
2352 | |
|
|
2353 | Example: simple class declaration and watcher initialisation |
|
|
2354 | |
|
|
2355 | struct myclass |
|
|
2356 | { |
|
|
2357 | void io_cb (ev::io &w, int revents) { } |
|
|
2358 | } |
|
|
2359 | |
|
|
2360 | myclass obj; |
|
|
2361 | ev::io iow; |
|
|
2362 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2363 | |
|
|
2364 | =item w->set<function> (void *data = 0) |
|
|
2365 | |
|
|
2366 | Also sets a callback, but uses a static method or plain function as |
|
|
2367 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2368 | C<data> member and is free for you to use. |
|
|
2369 | |
|
|
2370 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2371 | |
|
|
2372 | See the method-C<set> above for more details. |
|
|
2373 | |
|
|
2374 | Example: |
|
|
2375 | |
|
|
2376 | static void io_cb (ev::io &w, int revents) { } |
|
|
2377 | iow.set <io_cb> (); |
1728 | |
2378 | |
1729 | =item w->set (struct ev_loop *) |
2379 | =item w->set (struct ev_loop *) |
1730 | |
2380 | |
1731 | Associates a different C<struct ev_loop> with this watcher. You can only |
2381 | Associates a different C<struct ev_loop> with this watcher. You can only |
1732 | do this when the watcher is inactive (and not pending either). |
2382 | do this when the watcher is inactive (and not pending either). |
1733 | |
2383 | |
1734 | =item w->set ([args]) |
2384 | =item w->set ([args]) |
1735 | |
2385 | |
1736 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2386 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1737 | called at least once. Unlike the C counterpart, an active watcher gets |
2387 | called at least once. Unlike the C counterpart, an active watcher gets |
1738 | automatically stopped and restarted. |
2388 | automatically stopped and restarted when reconfiguring it with this |
|
|
2389 | method. |
1739 | |
2390 | |
1740 | =item w->start () |
2391 | =item w->start () |
1741 | |
2392 | |
1742 | Starts the watcher. Note that there is no C<loop> argument as the |
2393 | Starts the watcher. Note that there is no C<loop> argument, as the |
1743 | constructor already takes the loop. |
2394 | constructor already stores the event loop. |
1744 | |
2395 | |
1745 | =item w->stop () |
2396 | =item w->stop () |
1746 | |
2397 | |
1747 | Stops the watcher if it is active. Again, no C<loop> argument. |
2398 | Stops the watcher if it is active. Again, no C<loop> argument. |
1748 | |
2399 | |
1749 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2400 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1750 | |
2401 | |
1751 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2402 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1752 | C<ev_TYPE_again> function. |
2403 | C<ev_TYPE_again> function. |
1753 | |
2404 | |
1754 | =item w->sweep () C<ev::embed> only |
2405 | =item w->sweep () (C<ev::embed> only) |
1755 | |
2406 | |
1756 | Invokes C<ev_embed_sweep>. |
2407 | Invokes C<ev_embed_sweep>. |
1757 | |
2408 | |
1758 | =item w->update () C<ev::stat> only |
2409 | =item w->update () (C<ev::stat> only) |
1759 | |
2410 | |
1760 | Invokes C<ev_stat_stat>. |
2411 | Invokes C<ev_stat_stat>. |
1761 | |
2412 | |
1762 | =back |
2413 | =back |
1763 | |
2414 | |
… | |
… | |
1766 | Example: Define a class with an IO and idle watcher, start one of them in |
2417 | Example: Define a class with an IO and idle watcher, start one of them in |
1767 | the constructor. |
2418 | the constructor. |
1768 | |
2419 | |
1769 | class myclass |
2420 | class myclass |
1770 | { |
2421 | { |
1771 | ev_io io; void io_cb (ev::io &w, int revents); |
2422 | ev::io io; void io_cb (ev::io &w, int revents); |
1772 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2423 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
1773 | |
2424 | |
1774 | myclass (); |
2425 | myclass (int fd) |
1775 | } |
|
|
1776 | |
|
|
1777 | myclass::myclass (int fd) |
|
|
1778 | : io (this, &myclass::io_cb), |
|
|
1779 | idle (this, &myclass::idle_cb) |
|
|
1780 | { |
2426 | { |
|
|
2427 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2428 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2429 | |
1781 | io.start (fd, ev::READ); |
2430 | io.start (fd, ev::READ); |
|
|
2431 | } |
1782 | } |
2432 | }; |
1783 | |
2433 | |
1784 | |
2434 | |
1785 | =head1 MACRO MAGIC |
2435 | =head1 MACRO MAGIC |
1786 | |
2436 | |
1787 | Libev can be compiled with a variety of options, the most fundemantal is |
2437 | Libev can be compiled with a variety of options, the most fundamantal |
1788 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2438 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1789 | callbacks have an initial C<struct ev_loop *> argument. |
2439 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1790 | |
2440 | |
1791 | To make it easier to write programs that cope with either variant, the |
2441 | To make it easier to write programs that cope with either variant, the |
1792 | following macros are defined: |
2442 | following macros are defined: |
1793 | |
2443 | |
1794 | =over 4 |
2444 | =over 4 |
… | |
… | |
1826 | Similar to the other two macros, this gives you the value of the default |
2476 | Similar to the other two macros, this gives you the value of the default |
1827 | loop, if multiple loops are supported ("ev loop default"). |
2477 | loop, if multiple loops are supported ("ev loop default"). |
1828 | |
2478 | |
1829 | =back |
2479 | =back |
1830 | |
2480 | |
1831 | Example: Declare and initialise a check watcher, working regardless of |
2481 | Example: Declare and initialise a check watcher, utilising the above |
1832 | wether multiple loops are supported or not. |
2482 | macros so it will work regardless of whether multiple loops are supported |
|
|
2483 | or not. |
1833 | |
2484 | |
1834 | static void |
2485 | static void |
1835 | check_cb (EV_P_ ev_timer *w, int revents) |
2486 | check_cb (EV_P_ ev_timer *w, int revents) |
1836 | { |
2487 | { |
1837 | ev_check_stop (EV_A_ w); |
2488 | ev_check_stop (EV_A_ w); |
… | |
… | |
1840 | ev_check check; |
2491 | ev_check check; |
1841 | ev_check_init (&check, check_cb); |
2492 | ev_check_init (&check, check_cb); |
1842 | ev_check_start (EV_DEFAULT_ &check); |
2493 | ev_check_start (EV_DEFAULT_ &check); |
1843 | ev_loop (EV_DEFAULT_ 0); |
2494 | ev_loop (EV_DEFAULT_ 0); |
1844 | |
2495 | |
1845 | |
|
|
1846 | =head1 EMBEDDING |
2496 | =head1 EMBEDDING |
1847 | |
2497 | |
1848 | Libev can (and often is) directly embedded into host |
2498 | Libev can (and often is) directly embedded into host |
1849 | applications. Examples of applications that embed it include the Deliantra |
2499 | applications. Examples of applications that embed it include the Deliantra |
1850 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2500 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1851 | and rxvt-unicode. |
2501 | and rxvt-unicode. |
1852 | |
2502 | |
1853 | The goal is to enable you to just copy the neecssary files into your |
2503 | The goal is to enable you to just copy the necessary files into your |
1854 | source directory without having to change even a single line in them, so |
2504 | source directory without having to change even a single line in them, so |
1855 | you can easily upgrade by simply copying (or having a checked-out copy of |
2505 | you can easily upgrade by simply copying (or having a checked-out copy of |
1856 | libev somewhere in your source tree). |
2506 | libev somewhere in your source tree). |
1857 | |
2507 | |
1858 | =head2 FILESETS |
2508 | =head2 FILESETS |
… | |
… | |
1889 | ev_vars.h |
2539 | ev_vars.h |
1890 | ev_wrap.h |
2540 | ev_wrap.h |
1891 | |
2541 | |
1892 | ev_win32.c required on win32 platforms only |
2542 | ev_win32.c required on win32 platforms only |
1893 | |
2543 | |
1894 | ev_select.c only when select backend is enabled (which is by default) |
2544 | ev_select.c only when select backend is enabled (which is enabled by default) |
1895 | ev_poll.c only when poll backend is enabled (disabled by default) |
2545 | ev_poll.c only when poll backend is enabled (disabled by default) |
1896 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2546 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1897 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2547 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1898 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2548 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1899 | |
2549 | |
… | |
… | |
1948 | |
2598 | |
1949 | If defined to be C<1>, libev will try to detect the availability of the |
2599 | If defined to be C<1>, libev will try to detect the availability of the |
1950 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2600 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1951 | of the monotonic clock option will be attempted. If you enable this, you |
2601 | of the monotonic clock option will be attempted. If you enable this, you |
1952 | usually have to link against librt or something similar. Enabling it when |
2602 | usually have to link against librt or something similar. Enabling it when |
1953 | the functionality isn't available is safe, though, althoguh you have |
2603 | the functionality isn't available is safe, though, although you have |
1954 | to make sure you link against any libraries where the C<clock_gettime> |
2604 | to make sure you link against any libraries where the C<clock_gettime> |
1955 | function is hiding in (often F<-lrt>). |
2605 | function is hiding in (often F<-lrt>). |
1956 | |
2606 | |
1957 | =item EV_USE_REALTIME |
2607 | =item EV_USE_REALTIME |
1958 | |
2608 | |
1959 | If defined to be C<1>, libev will try to detect the availability of the |
2609 | If defined to be C<1>, libev will try to detect the availability of the |
1960 | realtime clock option at compiletime (and assume its availability at |
2610 | realtime clock option at compiletime (and assume its availability at |
1961 | runtime if successful). Otherwise no use of the realtime clock option will |
2611 | runtime if successful). Otherwise no use of the realtime clock option will |
1962 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2612 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1963 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2613 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1964 | in the description of C<EV_USE_MONOTONIC>, though. |
2614 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2615 | |
|
|
2616 | =item EV_USE_NANOSLEEP |
|
|
2617 | |
|
|
2618 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2619 | and will use it for delays. Otherwise it will use C<select ()>. |
1965 | |
2620 | |
1966 | =item EV_USE_SELECT |
2621 | =item EV_USE_SELECT |
1967 | |
2622 | |
1968 | If undefined or defined to be C<1>, libev will compile in support for the |
2623 | If undefined or defined to be C<1>, libev will compile in support for the |
1969 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2624 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
1987 | wants osf handles on win32 (this is the case when the select to |
2642 | wants osf handles on win32 (this is the case when the select to |
1988 | be used is the winsock select). This means that it will call |
2643 | be used is the winsock select). This means that it will call |
1989 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2644 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
1990 | it is assumed that all these functions actually work on fds, even |
2645 | it is assumed that all these functions actually work on fds, even |
1991 | on win32. Should not be defined on non-win32 platforms. |
2646 | on win32. Should not be defined on non-win32 platforms. |
|
|
2647 | |
|
|
2648 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2649 | |
|
|
2650 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2651 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2652 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2653 | correct. In some cases, programs use their own file descriptor management, |
|
|
2654 | in which case they can provide this function to map fds to socket handles. |
1992 | |
2655 | |
1993 | =item EV_USE_POLL |
2656 | =item EV_USE_POLL |
1994 | |
2657 | |
1995 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2658 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
1996 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2659 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2030 | |
2693 | |
2031 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2694 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2032 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2695 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2033 | be detected at runtime. |
2696 | be detected at runtime. |
2034 | |
2697 | |
|
|
2698 | =item EV_ATOMIC_T |
|
|
2699 | |
|
|
2700 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2701 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2702 | type is easily found in the C language, so you can provide your own type |
|
|
2703 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2704 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2705 | |
|
|
2706 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2707 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2708 | |
2035 | =item EV_H |
2709 | =item EV_H |
2036 | |
2710 | |
2037 | The name of the F<ev.h> header file used to include it. The default if |
2711 | The name of the F<ev.h> header file used to include it. The default if |
2038 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2712 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2039 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2713 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2040 | |
2714 | |
2041 | =item EV_CONFIG_H |
2715 | =item EV_CONFIG_H |
2042 | |
2716 | |
2043 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2717 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2044 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2718 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2045 | C<EV_H>, above. |
2719 | C<EV_H>, above. |
2046 | |
2720 | |
2047 | =item EV_EVENT_H |
2721 | =item EV_EVENT_H |
2048 | |
2722 | |
2049 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2723 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2050 | of how the F<event.h> header can be found. |
2724 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2051 | |
2725 | |
2052 | =item EV_PROTOTYPES |
2726 | =item EV_PROTOTYPES |
2053 | |
2727 | |
2054 | If defined to be C<0>, then F<ev.h> will not define any function |
2728 | If defined to be C<0>, then F<ev.h> will not define any function |
2055 | prototypes, but still define all the structs and other symbols. This is |
2729 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2062 | will have the C<struct ev_loop *> as first argument, and you can create |
2736 | will have the C<struct ev_loop *> as first argument, and you can create |
2063 | additional independent event loops. Otherwise there will be no support |
2737 | additional independent event loops. Otherwise there will be no support |
2064 | for multiple event loops and there is no first event loop pointer |
2738 | for multiple event loops and there is no first event loop pointer |
2065 | argument. Instead, all functions act on the single default loop. |
2739 | argument. Instead, all functions act on the single default loop. |
2066 | |
2740 | |
|
|
2741 | =item EV_MINPRI |
|
|
2742 | |
|
|
2743 | =item EV_MAXPRI |
|
|
2744 | |
|
|
2745 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2746 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2747 | provide for more priorities by overriding those symbols (usually defined |
|
|
2748 | to be C<-2> and C<2>, respectively). |
|
|
2749 | |
|
|
2750 | When doing priority-based operations, libev usually has to linearly search |
|
|
2751 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2752 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2753 | fine. |
|
|
2754 | |
|
|
2755 | If your embedding app does not need any priorities, defining these both to |
|
|
2756 | C<0> will save some memory and cpu. |
|
|
2757 | |
2067 | =item EV_PERIODIC_ENABLE |
2758 | =item EV_PERIODIC_ENABLE |
2068 | |
2759 | |
2069 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2760 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2070 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2761 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2071 | code. |
2762 | code. |
2072 | |
2763 | |
|
|
2764 | =item EV_IDLE_ENABLE |
|
|
2765 | |
|
|
2766 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2767 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2768 | code. |
|
|
2769 | |
2073 | =item EV_EMBED_ENABLE |
2770 | =item EV_EMBED_ENABLE |
2074 | |
2771 | |
2075 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2772 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2076 | defined to be C<0>, then they are not. |
2773 | defined to be C<0>, then they are not. |
2077 | |
2774 | |
… | |
… | |
2081 | defined to be C<0>, then they are not. |
2778 | defined to be C<0>, then they are not. |
2082 | |
2779 | |
2083 | =item EV_FORK_ENABLE |
2780 | =item EV_FORK_ENABLE |
2084 | |
2781 | |
2085 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2782 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2783 | defined to be C<0>, then they are not. |
|
|
2784 | |
|
|
2785 | =item EV_ASYNC_ENABLE |
|
|
2786 | |
|
|
2787 | If undefined or defined to be C<1>, then async watchers are supported. If |
2086 | defined to be C<0>, then they are not. |
2788 | defined to be C<0>, then they are not. |
2087 | |
2789 | |
2088 | =item EV_MINIMAL |
2790 | =item EV_MINIMAL |
2089 | |
2791 | |
2090 | If you need to shave off some kilobytes of code at the expense of some |
2792 | If you need to shave off some kilobytes of code at the expense of some |
… | |
… | |
2098 | than enough. If you need to manage thousands of children you might want to |
2800 | than enough. If you need to manage thousands of children you might want to |
2099 | increase this value (I<must> be a power of two). |
2801 | increase this value (I<must> be a power of two). |
2100 | |
2802 | |
2101 | =item EV_INOTIFY_HASHSIZE |
2803 | =item EV_INOTIFY_HASHSIZE |
2102 | |
2804 | |
2103 | C<ev_staz> watchers use a small hash table to distribute workload by |
2805 | C<ev_stat> watchers use a small hash table to distribute workload by |
2104 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2806 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2105 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2807 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2106 | watchers you might want to increase this value (I<must> be a power of |
2808 | watchers you might want to increase this value (I<must> be a power of |
2107 | two). |
2809 | two). |
2108 | |
2810 | |
… | |
… | |
2125 | |
2827 | |
2126 | =item ev_set_cb (ev, cb) |
2828 | =item ev_set_cb (ev, cb) |
2127 | |
2829 | |
2128 | Can be used to change the callback member declaration in each watcher, |
2830 | Can be used to change the callback member declaration in each watcher, |
2129 | and the way callbacks are invoked and set. Must expand to a struct member |
2831 | and the way callbacks are invoked and set. Must expand to a struct member |
2130 | definition and a statement, respectively. See the F<ev.v> header file for |
2832 | definition and a statement, respectively. See the F<ev.h> header file for |
2131 | their default definitions. One possible use for overriding these is to |
2833 | their default definitions. One possible use for overriding these is to |
2132 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2834 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2133 | method calls instead of plain function calls in C++. |
2835 | method calls instead of plain function calls in C++. |
|
|
2836 | |
|
|
2837 | =head2 EXPORTED API SYMBOLS |
|
|
2838 | |
|
|
2839 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2840 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2841 | all public symbols, one per line: |
|
|
2842 | |
|
|
2843 | Symbols.ev for libev proper |
|
|
2844 | Symbols.event for the libevent emulation |
|
|
2845 | |
|
|
2846 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2847 | multiple versions of libev linked together (which is obviously bad in |
|
|
2848 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2849 | |
|
|
2850 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2851 | include before including F<ev.h>: |
|
|
2852 | |
|
|
2853 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2854 | |
|
|
2855 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2856 | |
|
|
2857 | #define ev_backend myprefix_ev_backend |
|
|
2858 | #define ev_check_start myprefix_ev_check_start |
|
|
2859 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2860 | ... |
2134 | |
2861 | |
2135 | =head2 EXAMPLES |
2862 | =head2 EXAMPLES |
2136 | |
2863 | |
2137 | For a real-world example of a program the includes libev |
2864 | For a real-world example of a program the includes libev |
2138 | verbatim, you can have a look at the EV perl module |
2865 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2141 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2868 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2142 | will be compiled. It is pretty complex because it provides its own header |
2869 | will be compiled. It is pretty complex because it provides its own header |
2143 | file. |
2870 | file. |
2144 | |
2871 | |
2145 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2872 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2146 | that everybody includes and which overrides some autoconf choices: |
2873 | that everybody includes and which overrides some configure choices: |
2147 | |
2874 | |
|
|
2875 | #define EV_MINIMAL 1 |
2148 | #define EV_USE_POLL 0 |
2876 | #define EV_USE_POLL 0 |
2149 | #define EV_MULTIPLICITY 0 |
2877 | #define EV_MULTIPLICITY 0 |
2150 | #define EV_PERIODICS 0 |
2878 | #define EV_PERIODIC_ENABLE 0 |
|
|
2879 | #define EV_STAT_ENABLE 0 |
|
|
2880 | #define EV_FORK_ENABLE 0 |
2151 | #define EV_CONFIG_H <config.h> |
2881 | #define EV_CONFIG_H <config.h> |
|
|
2882 | #define EV_MINPRI 0 |
|
|
2883 | #define EV_MAXPRI 0 |
2152 | |
2884 | |
2153 | #include "ev++.h" |
2885 | #include "ev++.h" |
2154 | |
2886 | |
2155 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2887 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2156 | |
2888 | |
… | |
… | |
2162 | |
2894 | |
2163 | In this section the complexities of (many of) the algorithms used inside |
2895 | In this section the complexities of (many of) the algorithms used inside |
2164 | libev will be explained. For complexity discussions about backends see the |
2896 | libev will be explained. For complexity discussions about backends see the |
2165 | documentation for C<ev_default_init>. |
2897 | documentation for C<ev_default_init>. |
2166 | |
2898 | |
|
|
2899 | All of the following are about amortised time: If an array needs to be |
|
|
2900 | extended, libev needs to realloc and move the whole array, but this |
|
|
2901 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2902 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2903 | it is much faster and asymptotically approaches constant time. |
|
|
2904 | |
2167 | =over 4 |
2905 | =over 4 |
2168 | |
2906 | |
2169 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2907 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2170 | |
2908 | |
|
|
2909 | This means that, when you have a watcher that triggers in one hour and |
|
|
2910 | there are 100 watchers that would trigger before that then inserting will |
|
|
2911 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
2912 | |
2171 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2913 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2172 | |
2914 | |
|
|
2915 | That means that changing a timer costs less than removing/adding them |
|
|
2916 | as only the relative motion in the event queue has to be paid for. |
|
|
2917 | |
2173 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2918 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2174 | |
2919 | |
|
|
2920 | These just add the watcher into an array or at the head of a list. |
|
|
2921 | |
2175 | =item Stopping check/prepare/idle watchers: O(1) |
2922 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2176 | |
2923 | |
2177 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2924 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2178 | |
2925 | |
|
|
2926 | These watchers are stored in lists then need to be walked to find the |
|
|
2927 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2928 | have many watchers waiting for the same fd or signal). |
|
|
2929 | |
2179 | =item Finding the next timer per loop iteration: O(1) |
2930 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2931 | |
|
|
2932 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2933 | beginning of the storage array. |
2180 | |
2934 | |
2181 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2935 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2182 | |
2936 | |
2183 | =item Activating one watcher: O(1) |
2937 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2938 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2939 | on backend and wether C<ev_io_set> was used). |
|
|
2940 | |
|
|
2941 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
2942 | |
|
|
2943 | =item Priority handling: O(number_of_priorities) |
|
|
2944 | |
|
|
2945 | Priorities are implemented by allocating some space for each |
|
|
2946 | priority. When doing priority-based operations, libev usually has to |
|
|
2947 | linearly search all the priorities, but starting/stopping and activating |
|
|
2948 | watchers becomes O(1) w.r.t. priority handling. |
|
|
2949 | |
|
|
2950 | =item Sending an ev_async: O(1) |
|
|
2951 | |
|
|
2952 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
2953 | |
|
|
2954 | =item Processing signals: O(max_signal_number) |
|
|
2955 | |
|
|
2956 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
2957 | calls in the current loop iteration. Checking for async and signal events |
|
|
2958 | involves iterating over all running async watchers or all signal numbers. |
2184 | |
2959 | |
2185 | =back |
2960 | =back |
2186 | |
2961 | |
2187 | |
2962 | |
|
|
2963 | =head1 Win32 platform limitations and workarounds |
|
|
2964 | |
|
|
2965 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2966 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2967 | model. Libev still offers limited functionality on this platform in |
|
|
2968 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2969 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2970 | e.g. cygwin. |
|
|
2971 | |
|
|
2972 | There is no supported compilation method available on windows except |
|
|
2973 | embedding it into other applications. |
|
|
2974 | |
|
|
2975 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2976 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2977 | recommended (and not reasonable). If your program needs to use more than |
|
|
2978 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2979 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2980 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2981 | |
|
|
2982 | =over 4 |
|
|
2983 | |
|
|
2984 | =item The winsocket select function |
|
|
2985 | |
|
|
2986 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2987 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2988 | very inefficient, and also requires a mapping from file descriptors |
|
|
2989 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2990 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2991 | symbols for more info. |
|
|
2992 | |
|
|
2993 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2994 | libraries and raw winsocket select is: |
|
|
2995 | |
|
|
2996 | #define EV_USE_SELECT 1 |
|
|
2997 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2998 | |
|
|
2999 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3000 | complexity in the O(n²) range when using win32. |
|
|
3001 | |
|
|
3002 | =item Limited number of file descriptors |
|
|
3003 | |
|
|
3004 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3005 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3006 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3007 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3008 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3009 | |
|
|
3010 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3011 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3012 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3013 | select emulation on windows). |
|
|
3014 | |
|
|
3015 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3016 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3017 | or something like this inside microsoft). You can increase this by calling |
|
|
3018 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3019 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3020 | libraries. |
|
|
3021 | |
|
|
3022 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3023 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3024 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3025 | calling select (O(n²)) will likely make this unworkable. |
|
|
3026 | |
|
|
3027 | =back |
|
|
3028 | |
|
|
3029 | |
2188 | =head1 AUTHOR |
3030 | =head1 AUTHOR |
2189 | |
3031 | |
2190 | Marc Lehmann <libev@schmorp.de>. |
3032 | Marc Lehmann <libev@schmorp.de>. |
2191 | |
3033 | |